The disclosure of Japanese Patent Application No. 2000-003027 filed on Jan. 11, 2000 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to a child seat detecting apparatus, and more particularly to an apparatus and method for detecting a child seat mounted on a vehicle seat.
2. Description of Related Art
When a child is seated in a vehicle seat of a vehicle, the child seat must be secured to the seat and the child seated therein. The child seat is constructed so as to be secured to the seat using a seatbelt, so as long as there is a seatbelt the child seat can be mounted on the seat.
When the child seat is mounted on the passenger seat and an air bag deploys during a collision, the child seat is oppressed by the pressure from the air bag such that the child seated in the child seat receives the impact. Therefore, it is desirable to have the airbag automatically switch so as not to activate during a collision when a child seat is mounted on the passenger seat.
Research is being conducted on an apparatus (e.g. Japanese Patent Laid-Open Publication No. HEI 11-1153) constructed using a weight detecting apparatus that detects a load of a passenger seated in a vehicle seat in order to automatically determine whether a person not requiring a child seat is seated in the vehicle seat or whether a child seat is mounted on the vehicle seat.
This weight detecting apparatus includes a pair of seat rails that guide the vehicle seat back and forth and four load sensors disposed between a pair of seat brackets attached to the floor of the vehicle body. The front end portions and rear end portions of the pair of seat brackets are respectively supported by separate seat brackets and the four load sensors are mounted on the front end portions and the rear end portions of this pair of seat brackets mounted left and right.
Each load sensor is tightened and secured to the seat bracket as well as the seat rail with a bolt. In this construction when a passenger sits in the vehicle seat, a load corresponding to the weight of the passenger is distributed, activating the four sensors. Accordingly, the weight detecting apparatus mentioned above enables the weight of a passenger seated in the vehicle seat to be detected based on output signals from the four load sensors.
In determining the presence of a child seat with the weight detecting apparatus, however, the mounting of a child seat is determined based on the sum of all of the loads detected by the four load sensors. As a result, when a person of small stature yet who does not require a child seat, for example, is seated in the vehicle seat, the total load is substantially equivalent to that of a mounted child seat, making it difficult to determine whether a child seat is mounted on the vehicle seat or whether a person of small stature yet who does not require a child seat is seated in the vehicle seat.
Further, when a child seat detecting apparatus which uses a weight detecting apparatus determines that a child seat is mounted on the vehicle seat when actually a person of small stature yet who does not require a child seat is seated in the vehicle seat, there is a concern that the airbag may end up being set to a non-active state.
It is an object of the invention to provide a child seat detector constructed so as to be able to accurately determine whether a child seat is mounted on a vehicle seat or whether a person not requiring a child seat is seated in the vehicle seat.
In order to achieve the foregoing object, one aspect of the invention is a child seat detecting apparatus mounted on a vehicle seat, which is provided with a plurality of load sensors that detect a load applied to the vehicle seat and a controller that monitors a relative change of each load detected by the load sensors. The controller determines whether a child seat is mounted on the vehicle seat or whether a passenger is seated in the vehicle seat by the difference of change in load detected by each load sensor.
According to the foregoing aspect, monitoring the change of each load on the vehicle seat prevents incorrect detection of a child seat mounted on the vehicle seat even if a person of small stature yet who does not require a child seat is seated thereon.